Lever head designs of this kind are well known, for example, from the German patents DE-PS No. 17 59 520 and, DE-PS No. 26 58 022. In the case of the well known mixing valves, the mixing ratio and the volume can be determined with the hand lever which is arranged to move with two degrees of freedom. In these cases, the mixing ratio is determined by turning the lever head or swiveling the hand lever about the central axis of the lever head, while the total volume flowing is determined by up and down movement of the hand lever parallel to the central axis. This correlation of the two degrees of freedom of the hand lever often leads to undesirable overlapping of the two adjusting movements when operating the valve. When an adjustment is being made to alter the volume flow rate, it is easy for the lever head to be swiveled also, so that besides making the desired volume change, an undesirable change of the mixing ratio occurs at the same time. It is also easy when changing the mixing ratio for a preset volume to be changed undesirably.